Frequency control



H.;A. AFFEL March l, 1932.

FREQUENCY CONTROL vFiled March 1l. 1931 LNSAN QQ A A, NNN

j INVENTOR` l i BY iff/555% ATTORNEY i PmmeaMar.1,f193z f f HERMANy A. armor mnenwoon, NEw JERSEY; `A'ssrerfivcnt Tolamrcm tratan#A f i -riioNE AND TELEGRAPH COMPANY, Aconronarionor NEW Yoan y v f- FREQUENCY 'coNrnoL appiieation med Iman, 11931. ,serial Nuisances.

i invention relatesto yan'in'i'angement for rdetermining the phase and frev uencyof p a local source of current b means o a master v source, the wave lfrom w ich maybe trans-vV mitted over a l1ne. Such an arrangement has *application in connection with the s *chro'f nism of distant-radio stations and l' euses.k

In u, accordance with the present invention f itis proposed tocontrol the frequency of a .11 local source ofalternating current by trans'- mitting a control. frequency over a` ine circuit,y usingthe control frequency as a constant check on 'the frequency generated by the local source. Such an arrangement is particularly y l" advantageous because in case of failure ofthe line circuit which transmits the control frequency, thelocal'I generator will still function although its -frequency may not be accurately held. 4An arrangement of this sort also makesv f 2 yit more readily7 possible to minimize the effect of noise received fromV the line circuitand lto control the rate at. which the'incidental line changesare impressed on the local source.

. In accordance with oneembodiment of the invention, the sourcek of currentfwhose frequency is to be controlled may embody an os` f cillator whose frequency is stabilized by 'means of la ycrystal mounted in the yusual heat insulated chamber. Alternating currenty from yay master frequency source may be trans.- mitted overa line and after being stepped up x to the kfrequency assigned to the local' oscil-V n lator may be applied to'a detector together' f 315'with some ofthe'output from the local oscillator.l If the two applied waves rarcof the same amplitude, the output current willbe dependent y upon their phase relation and by. using this'outp'ut current toheat a resistance --in the heat yinsulated chamber, the frequency of thelocal oscillator may be changed, due

orks or `magneto-stii'ction` devices `would `obviously yalso lend themselves to temperature l y control of the l'same kind.y 'Y

The invention will now-be more derstood from the ,following description when 5 read in connection. with the accompanying on of the crystal, in such, a mannerk ydrawing the figure of which Ventionk.

y Referring tothe drawing,Ordesignaxtes'an' i j illustrateissehei matlcly e Pre'fenced embodiment of the inmounted withina heat insulating chamber C. l

A resistance` Ry in circuit'with a source of current B may be` used for n maintaining' the interior of the chamber-G at a ldesired normal temperature.; o 1 i" The master controlling frequency vmay be generated ,byfany suitable source at some distance station, such a source being'conven- `tionally illustrated inthe drawing at O. The

control wavev derived rfrom this source is then transmitted over a line L vtothe radio station- 'and' applied' to a kharmonic*generator HG which `steps the frequencyup to that of the rcarrier wavefassigned to the radio lstation. lThis high frequency current is then applied to the input offa ydetector D and some ofthe, energy from the oscillatorO is also applied tothe input fof said detector D; If desi-red, yboth waves may be `maintained at the same constant amplitude by means of constant 'output devicesy Yy and Yfg The output of the detector Dis connected to a heating" resistance Ralso mountedjin the heat insulating chamber C f y With this arrangement it will be apparent that if the controll wave and the controlled wave applied yto the detector Dare of equal amplitude, the detected current flowing" through they resistance R will depend Lupon the lphase relation-of the two waves, this current being a maximum. when the two waves cof arek inr exact synchronism and being a minio Therefore, if the two waves are normally so o rphased that an intermediate value of currflows through the resistance R. "This change in current changes the temperature of the mum when they are 180 degrees outof phase. 1 f

2S .'jWhatisclaimed is; y y .1. In ja ff equency contr'olsystem, means'to` generate a Wavelwhoselfrequency: is tob'e" 'fas thereby tending to. bring oscilla` rature lag ofthe.crystal'heateiysiemy will y m insure that''thesey changes lare yimparted tother 4system very gradually-so that they w1l1bea without' seriouszeect on the operationofithe, system. In. other words, the lag, oflthe. re-

' -slstance-R in translating change in current! 115 to change in temperature for the control of the crystal, will be sufficient to take up any 'small and 4rapid changesin 'the'apparent1- phase of the control frequency.: y

It-'will' bf obvious thatthe ygeneral ciples herein disclosed maybe embodied'in many other organizations WideIydi'erent y o from thoseiiillustratedfwithoutfdeparting fromthe spirit ofthe invention 'as deiine'd in the'follwmg' claims.

controlled, temperature responsive' ,meansl to vary the frequency of the fwave pgenerated,"y means to vsupply a controly wave., meansgre' v phase relation o'f the `control and controlled wave"` to 'produce temperature variations'to affect `said temperature responsive ymeans. i

/2. In a, frequencykcontrolsystern, means to generatesJ wave whose frequency istobe controlled, temperaturehresponsive means to vary the frequency oftheV wave generated,

' means to supply a controlwave, a' detectorto. which'said control and controlled waves may be' applied,"said detctor'hpr'odncinga current .varying with changesfinthe 'normal phase 'relation of thecontrol and"controlled'waves, and means totrans'late said currentinto heat .n 3.*111 a frequency Acontrols'ys'telngmeansto 'generate a Wave whose frequencyis 'to `be controlled, temperature responsivemeans to vary the frequency 4of the vvave generated, means to supplya control wave, a. detector to whichl said control and controlledrwaves may be applied,"sad detector' producingav currentuvarying with changes in` thenormal phase relationy ofthe control and Acontrolled t,

waves, andfa`-.heating 'element controlled-by said current, said heating, element being as!" saidy temperature responsive sociated with means.

50 generate a wave 'whose frequency is to be con'- trolled, temperature responsive means@ to varyfthe frequency of the Wave generated, means to supply a control wave, a'detector to which said control and controlled waves maybe applied saidfdetector producing a.

`spo'nsiye to temperature changesto vary the u i *generate a control wave at another station, a sponsive to certaln `changes inthe normal prmucing` a `current varying 'with changes t in theV normal phase relation of the control 'to affect said lternperat'urc'a"responsive,means.A a line tojfmnsmig Sai'dfwave to Said first Stacontrol fand controlled waves, and a heating element .controlled by said current, said he'atning element `being associated with said crysrcurrent varying lwithlchanges -infthe normal] phase. relation of the control and controlled perature changes so as to be relatively unresponsive; tolminor variations jin the phaserelation 'ofthe' control and ycontrolled wave.

` 5. `Inra frequency control systema crystal controlled,.oscillator at one station for generating a waye vvhose frequency is tob'e co'ntrolled', the crystal of said'oscillator being refrequency ofsaid oscillator, m'eans to generate ai controlfwave 'at another station,` a

' lineto ktransmit nsaid Wave to said first sta` 1tion5`meansat'said first stationl responsive v tokcertainchanges in the normal phase relationjofjthe"control andy controlled Wave to `prodiice temperaturev variations to affect said ocry'staL,v

o 6,2; Ina frequency controlksystem, a crystal controlledyosc'illator at one station for generatinga 'Wave `whose fre uency is tor becon-` trolled,"the crystal of said oscillator'being responsive toftemperature changes to vary the :frequency fof Asaid oscillator, means to line to transmit said wave to' said first station, a detector to'which said 'control and controlled waves may be'applied, said detector Vand controlledwaves, and means to translate'` said'cur'rent into heat't'o affect said crystal.' '7L Inf a frequency control system, 'a crystal controlled` oscillatorl aty one r'station for gen,- erating a`.vvave whose frequency istofbe con- .trolled,1thecrystal llof said-oscillator being responsive' totemp'erature changes to vary `thefrequency of said oscillator, means to generate'a'control wave atanother station, no tiona detectorv to which said control and controlled wavesV maybe applied, said def tectorproducing,` aV current varying with changes `in the normal, phase relation of the 4 8. In vafrequency control system, a. ycrystal controlled oscillator ,at one station yfor generating-a wavewhose frequency is tobe' controlled, the crystal of said oscillator beingrei f A- y 1 sponsivey totemperature changes to vary the 4. In a frequency control system, meansto f requency of said ,oscillatonmeans to gentotiansmit said wave to p said first station, 'adetector to' which saidcontrol and controlledgwavesv may be applied,isaid detector produclng a current varying withchanges in thenormalphase relation of the control and 13 y narrano controlled waves, yand aheating element con.. -trolled by said current, said heatingr element bein associated with said crystal and said heating.; element being suliiciently sluggish in the production of temperature changes so as to be relativelyunresponsive to minor "yariations inthe phase relations of the control; and controlled Wave.

9. In a frequency control system, a cr stal controlled oscillator at one station or generatingv a-wave whose frequency is to be controlled, the crystal of said oscillator being responsive to temperature changes to vary the frequency of said oscillator, means l5 to generate a control wave at lanotherstation, a line to transmit said wave to said first station, a detector to Whichsaid control and controlled waves maybe. applied,.said detector producing a current varyin with changes in the normal phase relation of the control and controlled waves, anda heating element controlled by said current, said heatin element beingassociatedwith said crysta and a heat insulated chamberenclosing said heating element and said crystal;

10. In a frequency control system involv ing a crystal controlled oscillator for gen- -erating the wave whose frequency is to be controlled, the method which consists in sup- 3 plying a control Wave,` producing temperature changes determined by Variations from the normal phase relation of the control and controlled waves, and applying sai-d temperature changes to the crystal of the oscillator 35, so as to'tend to bring the oscillator back into step with the control frequency. i u

1l. In a frequencycontrol 'system involv-` ing a crystal controlled oscillator forl generating the Wave whose frequency is to be con- 0 trolled, the method'which consists in supplying a control'wave, producing acurrent determinedv by variations from the normal phase relation of thecontrol and controlled waves, translating saidcurrent into corresponding temperature'changes, and applying the temperature changes to the crystal of said oscillator so as to tend to bring the oscillator back into step with the control frequency.

` In testimony whereof, I have signed my name to this specification this 20th day of February, 1931. I HERMAN A. AFFEL. 

